In ordinary metal processing metal parts are greased to avoid the corrosion process during their manufacture, storage and transport. Since the degreasing agent is incompatible with subsequent metal processing stages, a cleaning step to remove the metal protector is inevitable. Over the past few years, one of the major challenges in the area of metal degreasing has been the transition from fully emissive open-top systems based on the use of chlorinated solvents to closed-loop metal-degreasing systems based on low VOC emission, low toxicity solvents. Alternative chlorinated solvents such as trichloroethanol, chloroform, methyl chloride, CFC-113, HFCs, HCFCs, CO2 jets, scCO2, semi-aqueous solvents, alkaline cleaning agents, emulsifying detergent-based cleaners, and aliphatic hydrocarbon based solvents and azeotropic mixtures have been proposed to replace the widely used current industrial standard, namely trichloroethylene. However, none of the proposed alternatives fully satisfy the key industrial needs of the metal finishing sector.
Therefore the object of the present invention has been to develop new compositions allowing to perform metal degreasing operations in highly variable settings, with metal parts of different size and shape, minimizing diffuse emission, release of contaminated air during loading and unloading, and solvent release from cleaned metal parts. The use of these compositions should also avoid the generation of large waste streams, allowing to establish an easy and cost effective process in order to recycle solvent and rinsing water and ultimately delivering parts adequately conditioned for immediate use in subsequent steps of the metal finishing process. More particularly the present invention intends to replace commercial degreasing solvents known from the market by new compositions being more efficient, safer and friendlier to the environment.